The
twentieth century was the age of physics. The origins of today's
most visible artifacts  radios, telephones, television sets,
lasers, computers, space ships, and the atomic bomb  lie in
the discoveries of the twentieth-century physicists. And these are
only the visible side-effects.

At
times during this century, the pace at which nature's secrets
were being revealed seemed so great that physics appeared ready
to swallow the other sciences whole: first chemistry, then biology.
But physics does not exploit nature; that is left to engineering
and politics. Physics does not even try to explain, but only to
describe.

The
universe that physicists have painstakingly assembled during this
century is their greatest triumph. It is a universe in which galaxies
exist  an unknown fact until well into the century 
where stars are born and die, and where black holes gobble up
their remains. It is a universe of curved space, antimatter, and
supergravity, in which everything is comprised of mysterious stuff
called quarks, found in three families of two quarks each.

The
universe can be seen either as a swarm of particles, or as an
ocean of waves with equal clarity. It is a universe born in an
unfathomable primal explosion that may someday cease to exist.
It is a universe that, in J. B. S. Haldane's words. is not only
a queerer place than we imagined, but perhaps a queerer place
than we can imagine.

The
first Nobel Prize in Physics went to the German physicist Wilhelm
Röntgen in 1901. The selection and timing were right. At
the end of the nineteenth century, virtually every scientist believed
that the universe according to Isaac Newton and James Clerk Maxwell
 what is now called classical physics  was a complete,
accurate, and unassailable description of the fundamental laws
of nature. Alexander Pope's famous couplet:

Nature
and Nature's laws lay hid in the night:
God said, Let Newton be! and all was light.

had
achieved the status of scientific dogma.

Yet
cracks were already beginning to show in the grand edifice of
Newtonian physics, and what is now called the second scientific
revolution was ready to be launched. "It seems probable,"
said the American physicist Albert Michelson; "that most
of the grand underlying principles have been firmly established
. . . the future truths of physics are to be looked for in the
sixth place of decimals." Michelson's premature announcement
of the end of physics was made to a conference of scientists in
1894.

The
following year Röntgen discovered X-rays. The year after
that, the year of Alfred Nobel's death, the French physicist Antoine
Henri Becquerel discovered spontaneous radiation; in 1897, the
British physicist Joseph John Thomson deduced the existence of
electrons, which he called "corpuscles"; in 1898, Marie
Curie, the discoverer of radium and polonium, coined the term
"radioactivity". By the turn of the century the atomic
age had begun, and from it came what textbooks now refer to as
twentieth-century, or "modern", physics. In 1903 Becquerel
shared the Nobel Prize with Marie Curie and her husband Pierre;
Thomson became a laureate in 1906.

As
for Michelson, he lived to regret his statement, and received
a Nobel Prize in 1907 for his experiments in optics. Today, he
is best remembered for an experiment he conducted with chemist
Edward Morley in 1887, perhaps the most important failure in the
history of science. Michelson set out to prove the existence of
the so-called ether which at the time was thought (wrongly) to
pervade space. His failure to prove its existence was to become
the cornerstone of Albert Einstein's theory of relativity.

Einstein
received his Prize in 1921, but not for relativity. That theory
generally is acknowledged to be his most important work, along
with quantum theory, one of the two great triumphs of modern physics.
Instead, Einstein's Prize was for his work on the photoelectric
effect, one of the foundations of quantum theory, a theory that
Einstein himself never could accept.

The
roster of Physics laureates since and including Röntgen is
a remarkably representative list of the giants of twentieth-century
physics. "The Nobel has had a very good record," said
American physicist Leon Lederman not long after he won the Physics
Prize in 1988. Lederman is the former director of Fermilab, the
high-energy physics center in Illinois that was named after the
1938 Physics laureate Enrico Fermi. Lederman's ambition is to
reduce physics to a single equation. "... the biggest mistake
was Fermi," Lederman said. "They gave him the prize
for discovering transuranic elements when he really had discovered
fission. But that's the kind of mistake you like to make. There
have been very few mistakes, but some curious choices, like the
man who got the prize for inventing some kind of reflector for
lighthouses." (Lederman was referring to Swedish physicist
Nils Dalen, who received his prize in 1912 "for his invention
of automatic regulators in conjunction with gas accumulators for
illuminating lighthouses and buoys.")

There
have been unaccountable delays and strange omissions, of course:
Einstein waited seventeen years after the publication of his work
to receive his award, and Lederman himself waited almost three
decades. He used to tell his children the delay was because the
Nobel Committee "couldn't make up its mind which of my accomplishments
to recognize." And every physicist can name favourite theorists
or experimenters who should have won the Prize but did not.

The
most celebrated also-ran undoubtedly is the great New Zealand-born
physicist Ernest Rutherford, the first to uncover the structure
of atoms. Rutherford, who at age twenty-four went to England to
work with J. J. Thomson in 1895, was the consummate experimentalist:
a gruff, purposeful man one colleague described as graced with
an unparalleled gift for getting experiments to work by cursing
at them. Over his long career, Rutherford trained no fewer than
eleven Nobel laureates, and strongly believed he deserved a Physics
Prize of his own. In 1908 he did receive a Prize, but it was in
Chemistry. It distressed and bewildered him for the rest of his
life. He was, after all, the man who once declared "all science
is either physics or stampcollecting."

Looking
back over the careers of the more than 100 men and,women who have
won Nobel Prizes in Physics, the mix of experimentalists and theorists
is somewhat weighted toward the theorists; getting nature to yield
her secrets to experiment has become increasingly difficult and
expensive. Nevertheless, as 1923 Physics laureate Robert Millikan
put it, "science walks forward on two feet, namely theory
and experiment. Sometimes it is one foot which is put forward,
sometimes the other, but continuous progress is made only by the
use of both." Röntgen, on the other hand, made the case
for the experimentalists. When asked what he thought about while
he was discovering Xrays, Röntgen responded: "I
didn't think. I experimented." Einstein, who became the personification
of theoretical physics, much preferred "thought experiments"
to those conducted in a laboratory, but he realized the importance
of both.

As
the outstanding theoretical physicist Steven Weinberg stated in
his acceptance speech for the 1979 Prize he shared with Sheldon
Glashow and Abdus Salam: "Our job in physics is to see things
simply, to understand a great many complicated phenomena in a
unified way, in terms of a few simple principles. At times, our
efforts are illuminated by a brilliant experiment . . . but even
in the dark times between experimental breakthroughs, there always
continues a steady evolution of theoretical ideas, leading almost
imperceptibly to changes in previous beliefs."

What
is most surprising about the roster of Physics laureates is how
few of these men and women  among them some of the most
brilliant minds of this century  achieved wide public recognition
outside the realm of science. Even before he received his Nobel
Prize, Einstein was a worldwide celebrity, but, with the possible
exception of the Curies and Marconi, it is difficult to think
of a Physics laureate who is as well known as even a minor rock
star.

The
relative obscurity of the majority of Nobel Prizewinning physicists
is due both to the language of physics  mathematics, a language
that translates poorly  and the mind-boggling universe it
describes. The great British astronomer Arthur Stanley Eddington
clarified the problem when he was interviewed shortly after the
publication of the theory of relativity, an idea that physicists
say is a stroll in the woods compared to the thorny jungle of
quantum theory. When asked if it was true that only three people
in the world understood Einstein's theory, Eddington quipped,
"Who is the third?"

In
the world of science, however, the roster of Nobel Physics laureates
could double as an honour roll of the most famous names of the
century. A brief list of eponyms makes the case: Planck's constant
(after Max Planck, who received the Prize in 1919); the Compton
effect (Arthur Compton, 1927); De Broglie waves (Prince LouisVictor
de Broglie, 1929); the Heisenberg uncertainty principle (Werner
Heisenberg, 1933); Cerenkov radiation (Paver Cerenkov, 1958);
Josephson junctions (Brian Josephson, 1973); and Feynman diagrams
(Richard Feynman, 1965)  to name only a few. A number of
Physics laureates have been awarded the singular honour of having
their names given to units of measurement the rontgen, the
curie, and the fermi come to mind. Einstein had an element of
nature named after him: einsteinium, the ninety-ninth element,
discovered shortly after his death; the 102nd element, first isolated
in Sweden in 1958, was named nobelium after Alfred Nobel.

Outside
the world of science, there is a popular if distorted picture
of the physicist as a down-to-earth scientist whose discoveries
immediately and irrevocably change the way we live. In some ways,
Röntgen fits that description: barely a month after the discovery
of X-rays, Eddie McCarthy of Cartmouth, New Hampshire became one
of the first to have his broken arm set by a physician using X-ray
images.

Marconi's
wireless had a similar impact on everyday life, as did the discovery
of colour photography by French physicist Gabriel Lippman (1908
laureate); the development of laser theory by American physicist
Charles H. Townes (1964); and the invention of the transistor
by American physicists William Shockley, Walter Brattain, and
John Bardeen (1956 laureates). To date, Bardeen is the only laureate
to win two Physics Prizes. He was honoured again in 1972 along
with Leon Cooper and Robert Schrieffer for work in developing
a theory of superconductivity, which may change the way we live
in the not-too-distant future.

Of
course, the most visible and ominous invention of twentieth-century
physics was the atomic bomb, the result of work by a long list
of Nobel laureates, Einstein among them. The bomb itself was the
by-product of an effort to solve the most intriguing problem of
modern science, namely, what is the structure of the atom and
how do its parts behave? "The constitution of the atom is,
of course, the great problem that lies at the base of all physics
and chemistry," said Lord Rutherford early in the century,
"and if we knew the construction of atoms we ought to be
able to predict everything that is happening in the universe."
Today's physicists no longer accept Rutherford's promise of prediction
 not since 1933 when laureate Werner Heisenberg abolished
the notion of absolute certainty in science  but the central
question remains the same.

Over
the course of the century, the majority of Physics laureates have
devoted their lives to understanding the workings of the atom
and its parts. Because of the nature and complexity of this effort,
the results and breakthroughs more often than not are beyond the
grasp of the general public. Nobel's Physics Prize, in a sense,
makes up for this lack of general recognition, and there is no
doubt that it is cherished as much for its prestige in the community
of physicists as for its monetary reward.

Consider
the case of Nils Bohr, the Danish physicist who won the Prize
in 1922 for "his services in the investigation of the structure
of atoms and of the radiation emanating from them". The torch-bearer
of the quantum revolution, Bohr donated his Nobel medal to Finnish
war relief at the beginning of the Second World War. Soon after
the War began he was entrusted with the medals of the German physicists
Max von Laue (1914 laureate) and James Franck (1926). Before he
escaped from occupied Denmark in 1943, Bohr, a meticulous man
who was known to write drafts of postcards, dissolved the medals
in acid in order to get them safely out of the country. After
the War, he precipitated the gold from the acid, and had the medals
re-cast.

As
this century comes to a close, the picture of the universe provided
by modern physics appears fairly complete. It describes a universe
that operates according to the laws of quantum mechanics and relativity,
and is governed by four basic forces  gravity, electromagnetism,
weak nuclear, and strong nuclear. The forces themselves are mysteries;
nobody can explain them. Physicists call them explanatory principles
which themselves cannot be explained, but they nevertheless govern
the behaviour of everything from electrons to elephants.

As
the new century approaches, the dream of physicists is to combine
these four mysteries into one, to successfully marry quantum mechanics
and relativity and produce a single set of simple, elegant equations
that perfectly describe the first moment of time and everything
since then: a theory of everything.

Some
physicists, among them the British physicist Stephen Hawking,
predict that such a theory is close to hand. Others point to Michelson's
announcement of the death of physics in 1894, and Max Born's prediction
in the late 1920s that "Physics as we know it will be over
in six months." The answer to the question of physics' ultimate
demise will probably not be settled until the next century. But
then in physics, answers have never been as important or interesting
as the questions.

It
is the questions, not the answers, that are the triumphs of twentieth-century
physics. How did the universe begin? How will it end? Will time
someday reverse itself? What goes on inside the atom? If space
is primarily empty, why does the ground hold us up? Why is the
sky dark at night? In posing these questions in a unique, precise
way, physics in this century has extended the sphere of human
knowledge, illuminating regions previously explored only by philosophers
and children.